1. Field of the Invention
The present invention pertains to the treatment of the class of solid materials called particulates that includes assemblies of matter in individual units of size of about one inch or less.
2. Background Description and Brief Discussion of the Related Art
Particulate matter may have various origins. They may occur in nature, such as metal or petroleum sources, or they may be man-made, such as chips or filaments that are cut from the surfaces of metal bars during lathe processing. For each of these types, the particulate matter is in need of some kind of treatment, be it either elimination of a contaminant and impurity or the recovery of a valuable component. In either case, removal of a component from the particulate is a necessary step for a subsequent, value-added product.
For example, titanium machining chips are valuable and are re-melted and recycled for subsequent use. However, titanium machining chips get contaminated with a residual cutting oil, and the oil creates metallurgical problems during melting and casting of the metal. Therefore, it is critical that the oil be removed from the chips before they are recycled and reused.
In most currently available cleaning systems and processes, the contaminated chips are washed in a large volume of scalding hot water with very high levels of caustic cleaning agents. However, such cleaning systems and processes disadvantageously result in a liquid by-product of high pH. Such systems and processes also disadvantageously require the cleaning solution to reach relatively high temperatures, require sufficient caustic chemical cleaning agents to achieve the desired high pH, and require subsequent neutralization treatment of the effluent solution in order to avoid dealing with a hazardous waste. These requirements, individually and in combination, result in a high treatment cost and a relatively large amount of by-products.
Several alternative processes can be considered in place of the cleaning process described above. First, a treatment process may employ enzymatic agents; but, while such a process reduces temperature requirements and alleviates the waste concerns, the enzymes that are required disadvantageously are expensive and are terminal in use as they are disposed of in the by-product. As another possible technique, the chips may be chemically treated with a strong nitric and hydrofluoric acid solution, but disposal of the liquid by-product would be hazardous since it would contain quantities of the fluoride ion. As yet another possible technique, titanium chips may be cleaned with a spray of tiny abrasive glass particles, but adhesion of the glass particles to the surfaces of the oil coated chips reduces the effectiveness of this process.